Before diving into screens, APIs, and safeguards, let’s start with the job. Our blockchain-powered app (Yarsha & Wapal) helps connect. The fastest way to get a brand-new user to that “aha” moment is to let them sign in with something they already understand: their phone number.
Phone number login removes the steep learning curve of wallet-first onboarding. Many new users stall at “install a wallet,” “save this seed phrase,” or “paste your 0x… address.” OTP is familiar, fast, and passwordless. It reduces the steps between “open app” and “first mint or claim.”It also shrinks support tickets around initial setup because users already know how SMS codes work on Web3 blockchain platforms.
Why Phone Number + OTP, Not Wallet-First?
Now that we’re aligned on the problem, let’s connect it to the solution approach. A phone-first, OTP login is not “less web3.” It simply defers complexity until the user is ready. We start with something every smartphone user can do, then progressively reveal wallet features.
Here’s why this wins over wallet-first in practice.
Friction at Signup with Wallet
Wallet-first onboarding asks a lot: install an extension or app, create a wallet, back up a seed phrase, figure out what a public address is, and approve connections. Each step is a chance to drop off. In contrast, entering a phone number and a 6-digit code is simple and universal.
Progressive Disclosure: Log in Now, Link Wallet Later
With OTP login, we can create a normal session immediately. Users can browse collections, claim a free NFT, or start a low-risk mint. When they need advanced actions, we prompt them to link an existing wallet or create a managed one.
Impact on Conversion and Activation
Less friction at signup results in more people completing the flow. That’s the activation moment that matters for mobile apps. In practice, teams that switch to OTP login typically see higher completion rates and fewer support escalations tied to wallets in the first session.
User Journey
The user journey below shows a new user’s steps, from the first screen to optional wallet actions. We’ll keep the flow simple, then expand the details later for engineers.
Enter Phone Number
The first screen asks for a phone number. We automatically format it to the E.164 standard (country code + number) so the backend and SMS provider receive a consistent, valid value. A small checkbox or line of text captures consent to receive one-time codes.
Receive and Enter 6-digit OTP
The user receives a 6-digit code by SMS. On modern devices, the code often auto-fills. The OTP should expire quickly (for example, two to five minutes). We show a clear countdown, allow a resend with backoff, and keep errors readable and straightforward.
Immediate Access
After verifying, we create a session (for example, a short-lived JWT plus secure cookies). The user can immediately browse, claim a starter collectible, or run a low-stakes mint. No wallet is required at this stage.
Link Existing Wallet
If the user wants to trade, withdraw, or bring assets from elsewhere, present a “Link wallet” sheet. They can connect via WalletConnect/deep link. We store a signed challenge proving control of that wallet and link it to the session.
Architecture Overview
A smooth UX relies on a clean architecture. Before listing endpoints, let’s connect the journey to the main components behind it. The idea is to keep trust boundaries clear and each service small and testable.
Components: Auth API, OTP Provider, Session service, Wallet service
- Auth API issues and verifies OTPs. It talks to an OTP provider (SMS/voice/WhatsApp) and returns a request_id for the code.
- Session service creates and validates sessions (JWTs/cookies), sets expiries, and rotates tokens as needed.
- Wallet service manages wallet linking (signature challenges) and, if enabled, creates a managed (custodial/MPC) wallet on demand.
Data Model: User, Phone (E.164), session, wallet link state
We store a user record, a normalized phone number (E.164), and a session record. If the user links a wallet, we store the wallet address, the signature that proves control, and the link status. If we create a managed wallet, we store its identifiers and recovery status.
Integration Guide (Frontend: Web / React Native)
The frontend’s job is to make the process fast and forgiving. Before listing screens, let’s connect UX choices to error reduction: fewer fields, fewer taps, and helpful defaults dramatically improve completion.
Phone Number Screen
- Show a country picker and format as E.164.
- Offer clear consent text (“We’ll send a one-time code.”).
- Disable the button until the number looks valid.
- Use copy that promises value (“No passwords. No wallet required to start.”).
OTP screen
- Auto-advance digits and support paste.
- Show a timer and a “Resend code” button with exponential backoff.
- Surface delivery problems early: “Didn’t get a code? Try voice call or email.”
- On success, navigate directly to something rewarding (claim, browse, or mint).
Error States and Edge Cases
Handle devices with no SIM (Wi-Fi tablets), roaming numbers, and users who mistype. Keep error messages clear and non-technical. Offer channels that work in low-coverage regions (voice call can help).
Post-Login Sheet: Link or Create Wallet
After the first session is live, show a simple sheet: Link your wallet (for advanced actions) or Create a wallet. Make it skippable. Keep the benefit text short: “Link to trade or withdraw; skip to keep exploring.”
Security & Privacy
Security is not a feature you add later; it’s how the whole flow behaves. Before listing controls, connect risk to context: OTP is ideal for onboarding and everyday use, but safeguards must be added for high-value actions.
SIM-Swap Mitigations
- Keep OTP TTL short and limit attempts.
- Step-up re-verification is required for sensitive actions (selling, exporting, large transfers).
- Consider adding a second factor for high-risk changes (email or passkey).
Undelivered OTP Handling
If delivery fails repeatedly, switch channels: voice call, WhatsApp, or a magic link to email (with explicit user consent). Show a help link and keep retries polite, not spammy.
Device/Session Hardening
Record basic device and IP metadata to detect suspicious patterns. If risk spikes (new device and new country in minutes), apply additional checks or temporarily limit actions.
Regional Compliance & Sender ID Strategy
Work with sender IDs and templates that comply with carrier rules in each region. Maintain a small set of approved message templates to improve deliverability.
UX Guidelines
Good UX makes security and reliability invisible. Before listing specific guidelines, connect UX choices to outcomes: clear copy and accessible flows increase completion and reduce frustration.
Copy & Micro-Interactions
- Use simple language: “We have sent a code,” not “An authentication token has been dispatched.”
- Show progress and confirmation states.
- Avoid blame in errors: “This code doesn’t match. Try again or request a new one.”
Accessibility
- Label inputs clearly and support screen readers.
- Manage focus so the cursor moves to the next OTP digit automatically.
- Provide sufficient contrast and large tap targets.
Localization & Number Formatting Best Practices
- Localize field labels and error messages.
- Format numbers according to local conventions, but always send E.164 to the backend.
- Handle right-to-left languages gracefully.
Analytics & Success Metrics
Analytics proves the value of the change and shows where to tune it. Before detailing metrics, connect them to the business goal: more completed signups, faster first actions, and fewer support issues.
- Measure the number of users who start and finish the flow. Compare phone login to wallet-first baselines to see the lift.
- Track the time from successful OTP verification to the first claim or mint. The closer this is to a few minutes, the better the experience.
- Track the number of power users who link an external wallet and new users who accept a managed wallet. Use these numbers to improve prompts and timing.
- Monitor resend rates. High resends often indicate deliverability issues. Break down by carrier and region to find problems quickly.
- Track tickets that mention login, OTP, and wallet connection. The goal is fewer tickets and faster resolution thanks to clearer flows.
Conclusion
The simplest way to welcome mainstream users into blockchain platforms is via phone number and OTP login. Mokshya can help you ship this end-to-end, combining Web3 onboarding, smooth wallet integration, and strong security. We design and build production-grade Web3 platforms with phone OTP and seamless wallet link/create flows.
Let’s talk if you’re ready to turn smoother onboarding into real adoption; Mokshya will help you launch in weeks, not months.